Full-length proviruses of baboon endogenous virus (BaEV) and dispersed BaEV reverse transcriptase retroelements in the genome of baboon species

Baboon endogenous virus (BaEV) is present in multiple copies in many Old World monkey species. BaEV proviruses may contain open reading frames for all major genes, as is indicated by the rescue of infectious virus particles from baboon and gelada tissues after cocultivation with permissive cells. We have analyzed full-length BaEV proviral structures in a baboon (Papio cynocephalus) genomic library and found no evidence for the rearrangements or large deletions commonly observed in endogenous virus genomes from other mammalian species. The two proviruses studied were integrated next to or nearby long interspersed repeat sequence (LINE) transposable elements. Additionally, isolated dispersed fragments with 100% and approximately 77% homology, respectively, to part of the BaEV reverse transcriptase gene were detected. These presumed retroelements were present in an approximately 10-fold excess compared with the full-length proviral genomes. PCR amplification and sequencing of BaEV reverse transcriptase and env fragments from the lambda clones and from the genomic DNA of other baboon species showed that there is little sequence variation present in BaEV DNA in the baboon genome.